Power line coupling device



May 28,1968

L. B. STEIN, JR. ETAL POWER LINE COUPLING DEVICE Filed Oct.

4 Sheets-Sheet 2 FIGS INVENTORS. LAURENCE B. STEIN/ JR.

CHARL ES W4 SSERMAN A TTO ENE Y5.

-May 28, 1968 L. B. STEIN, JR. ETAL POWER LI NE COUPLING DEVICE FiledOct. 21, 1965 FIGH 4 Sheets-Sheet 5 4% gas Will/BLUE S F i wmrg ELK/BLUEaLAcK (F) 5 D (s) mvsmoes.

LAURENCE B. STEIN, JR.

Y CHARLES WASSERMAIV A T TORIVE Y5.

United States Patent 3,386,059 POWER LINE COUPLING DEVICE Laurence B.Stein, Jr., Hingham, Mass, and Charles Wasserman, Baltimore, Md.,assignors to Sigma Instruments, Inc., a corporation of MassachusettsContinuation-impart of application Ser. No. 301,516, Aug. 12, 1963,which is a continuation-in-part of application Ser. No. 338,096, Jan.16, 1964. This application Oct. 21, 1965, Ser. No. 500,109

9 Claims. (Cl. 336-84) ABSTRACT OF THE DISCLOSURE A coupling device forinductive coupling to a high voltage power line conductor, and servingas a fixed insulating support for the conductor, is disclosed asincluding a high voltage hollow insulator having a closed outer and anopen inner end, with the exterior of the outer end having means forreceiving a current conductor and enabling the insulator to be locatedin predetermined angular orientation with respect to the longitudinalextent of the supported conductor. One or more coils are mounted withinthe insulator adjacent the closed outer end thereof, with the axes ofthe coils in predetermined orientation with respect to the conductor,and with the coil or coils spaced inwardly from the conductor. A closureof highly electrically conductive and non-magnetic metal encloses thecoil or coils within the insulator, and the coil leads are brought outthrough the enclosure to terminals thereon. A metal base covers the openend of the insulator and output leads extend from the coil terminals ininsulated relation through the base, the base being sealed on the openinner end of the insulator. The base may have a nipple extendingtherefrom and supporting one element of a known type of electricalconnector, for connection to a mating element of such known type of anelectrical connector.

The metal enclosure for the coils is preferably supported on a hollowtube extending longitudinally of the insulator, and the insulator may befilled with insulating compound or may have a dielectric gas, under highpressure, supplied to the interior thereof, or both expedients may beused.

The present application is a continuation-in-part of copendin-gapplication Ser. No. 301,516, filed Aug. 12, 1963, now abandoned, andcopending application Ser. No. 338,096, filed Jan. 16, 1964, now PatentNo. 3,251,- 014, issued May 10, 1966.

The increasing use of electricity has required higher voltages for thetransmission and distribution of electric power. correspondingly, thishas resulted in greater complexity of transmission and distributionarrangements, and in an increased need for means for measuringaccurately and conveniently the current in the transmission anddistribution circuits for the purposes of relaying, metering andcontrol.

Known arrangements for measuring the current of transmission anddistribution line conductors involves the use of current transformers.Current transformers are relatively expensive, difficult to install, andrequire separate supporting arrangements. Among the diffic-ultiesinvolved is that it is necessary to cut or break the line in order toconnect the current transformer into the line.

Thus, the installation of such devices has required elaborate safetyprecautions as well as necessitating the temporary shutdown of atransmission or distributing line. Such closing down of a line is notalways convenient and frequently may be undesirable due to interruptionof power to a load or consumer. Consequently, there has been a long feltneed for a simple and inexpensive means for coupling to a transmissionor distribution power line without interruption of delivery of powerover the line, and without breaking into the line or making physicalconnections thereto.

It is a well known fact that any line conductor having current flowingtherethrough is surrounded by a magnetic field and an electric fieldwhich have parameters determined by the current being carried by theconductor. For this reason, it is possible to make an inductive couplingto a current carrying line to pickmp inductively a voltage or currentwhich is proportional to the current being carried by the line. However,in practice, such inductive coupling to a line is difiicult to effect ina practical manner, and expedients used hitherto have not beensa'isfactory from a commercial standpoint. As a matter of fact, mostinductive pick-ups hitherto proposed have been of the manual probe-typearranged to be manually positioned in operative association with acurrent carrying conductor, and none have been designed for permanentinstallation with relation to the current carrying conductor.

A difficulty encountered with prior art inductive pickups has been thatof the sensitivity of the pick-up coil to current surges and otherdisturbances, as well as the difficulty of protecting the coil againstcorrosion. A further difiiculty has been encountered in obtaining aninductively coupled signal which is of a magnitude suitable for use inrelaying, metering, or other control purposes.

Another difficulty with known pick-up arrangements has been that ofproviding the proper dielectric separation or insulation between thecurrent carrying conductor and the controls. As disclosed in theabove-mentioned copending applications, a simple and inexpensivesolution to the foregoing problems involves the use of a hollow ortubular insulator post for supporting the current carrying conductor,this post serving also as a permanent support for the conductor, eitheras a station post or a line post. Within this hollow insulator there isdisposed an inductive pick-up coil which has a predetermined orientationwith i'elaton to a line conductor supported on the outer end of thepost. Leads are brought from the coil through the hollow insulator postand out through the other end thereof, whereby the current in the coilmay be used for relaying, metering, or other control purposes. In onearrangement, the closed end of the hollow post insulator is formed witha groove extending diametrically thereacross, and the coil within theinsulator and adjacent this closed end has predetermined orientationwith respect to this groove.

The advantage of this arrangement is that an effective insulation of theline conductor from the control instruments is provided by the hollowpost insulator, and the latter furthermore acts not only as a permanentsupport for the line conductor, but also as an enclosure for the pick-upcoil. It is not necessary to make electrical connections to the lineconductor, to cut into the line conductor or to surround the conductor,as in the use of a current transformer, in order to obtain the controlsignals, as the latter are obtained inductively.

An object of the present invention is to provide an improved couplingdevice serving as a permanent support for a power line conductor andalso serving to couple control instruments inductively to the lineconductor without electrical connection to the latter.

Another object of the present invention is to provide an improvedelectrical coupling device serving as a permanent insulating support fora line conductor and including at least one pick-up coil and meansprotecting the winding of the pick-up coil from line surges and otherdisturbances, such as high transient voltages and currents.

A further object of the invention is to provide an electric couplingdevice serving as a permanent insulating support for a current carryingpower conductor and enclosing means for inductively coupling controlinstruments to the power conductor, as well as including means wherebythe coupling device may be readily, easily and simply compensated forvarious widths or extents of power conductors such as bus bars and thelike.

Yet another object of the invention is to provide an electric couplingdevice for coupling to a current carrying power conductor and includinga hollow post insulator serving as a permanent insulator support for thepower conductor, such as a bus bar, transmission line or distributionline, this hollow post insulator enclosing inductive pick-up means andcompensating means whereby the inductive pick-up means may be adaptedand adjusted for conductors having various effective distances outwardlyof the hollow post insulator.

Still a further object of the invention is to provide an electriccoupling device of the type just mentioned including novel meansprotecting the inductive pick-up means against transients, surges andthe like, as well as against atmospheric corrosion.

A further object of the invention is to provide an electric couplingdevice including a hollow post insulator serving as a permanentinsulator support for a power line conductor, such as a bus bar,transmission line, or distribution line, this insulator enclosinginductive pickup coils and compensating coils in association with thepick-up coils, and the inductive pick-up coils being constructed forgreatly improved and more efficient inductive pick-up of energy from thepower line conductor.

Yet another object of the invention is to provide an electric couplingdevice of the type just mentioned including a fitting on the inner endof the hollow post insulator providing for-various mounting arrangementsand accessibility to coil secondary leads.

A further object of the invention is to provide an electric couplingdevice serving as a permanent insulator support for a current carryingpower line conductor, such as a bus bar, transmission line, ordistribution line, and in which measurement of the current in the highvoltage conductor is obtained without altering the physical arrangementof the major equipment supporting the conductor.

Still another object of the invention is to provide an electric couplingdevice of the type just mentioned including means for maintaining areasonably constant relation between the primary current and thesecondary output with various positions and shapes of primary power lineconductors.

For an understanding of the principles of the invention, reference ismade to the following description of typical embodiments thereof asillustrated in the accompanying drawings.

In the drawings:

FIG. 1 is a schematic wiring diagram illustrating one embodiment of theinvention electrical coupling device incorporated in a system for powerfactor correction;

FIG. 2 is an elevation view, partly in section, illustrating the generalconstruction and assembly of the electrical coupling device of theinvention;

FIG. 3 is an inner end view of a coil assembly and enclosureincorporated in the coupling device;

FIG. 4 is a part sectional and part elevation view taken on the line 4-4of FIG. 3;

FIG. 5 is a part sectional and part elevation view taken on the line 55of FIG. 3;

FIG. 6 is a sectional view through an electrical coupling deviceembodying the invention and used as a line post insulator for a highvoltage, current carrying power conductor;

FIG. 7 is a partial elevation view of the coupling device shown in FIG.6, looking from the right of FIG. 6;

FIG. 8 is a sectional view of a pick-up coil assembly incorporated inthe coupling device shown in FIGS. 6 and 7;

FIG. 9 is an inner end view, partly broken away, of the coil assembblyshown in FIG. 8;

FIG. 10 is a sectional view taken on the line 10 10 of FIG. 8;

FIGS. 1 1 and 12 are sectional views taken on the correspondinglynumbered lines of FIG. 9;

FIG. 13 is a sectional view of "an electrical coupling device embodyingthe invention and used as a station post insulator support for a highvoltage current carrying bus bar or other power conductor;

FIG. 14 is a partial elevational view of a support base, included in thecoupling device shown in FIG. 13, and looking from the right of FIG. 13;

FIG. 15 is an elevation view, partly in section, of a coil assembly usedin the coupling device shown in FIGS. 13 and 14;

FIG. 16 is an inner end view, partly broken away, of the coil assemblyshown in FIG. 15; and

FIG. 17 is a schematic wiring diagram of the coils included in theassembly shown in FIGS. '15 and 16.

'As stated, the electrical coupling device of the invention may be usedin any case Where it is desired to provide metering, relaying, phasecontrol, or other control operations in accordance with the currentflowing through a high voltage transmission line, distribution line, orstation bus bar. For example, the electrical coupling device may be usedin a power factor control arrangement such as illustrated in FIG. 1.Referring to FIG. 1, an electrical coupling device 20 embodying theinvention is shown in operative relation with one phase of a three-phasehigh voltage AC. power distribution line, this one phase including highvoltage, current carrying line conductors 21 and 22. Solely by way ofexample, coupling device 20 is illustrated as mounted on a suitablesupport, such as a cross-arm v23, and as serving as a permanentlymounted insulating support for line conductor 21.

A transformer 25 is connected across the line conductors 2-1 and 22, andhas a secondary winding 24 which may have a 120 volt output. Secondarywinding 24 is connected to terminals 3-1, 32 of a control apparatuswhich is described in detail in U.S. Patent No. 3,091,731. Controlapparatus 30 has terminals 3 3 and '34 connected to electrical couplingdevice 20 which, as stated, serves as a permanent insulating support forline conductor 21. As will be described more fully hereinafter, couplingdevice 20 includes one or more coils inductively coupled to line 211 forinductively deriving a voltage in accordance with current flowingthrough line 21, and without the necessity of either breaking into line21 or making any electrical connections thereto.

Control apparatus 30 has output terminals 36 and 37. Conductors '26 and27 connect output terminals 36 and 37 to a suitable switching device 38,and a neutral, which may be obtained from terminal 3-2, is connected bya conductor 28 to device 38. Switching device 38 may be an oil circuitbreaker for connecting and disconnecting a capacitor 65 relative to thetransmission line 21, 22.

Apparatus 30 compares the voltage of secondary winding 24, which isrepresentative of the voltage across transmission line 21, 22 and whichis of substantially constant phase relative to the transmission linevoltage, with an electrical quantity supplied by the coupling device 20.This electrical quantity corresponding in magnitude and phase angle tothe current through the transmission line 21. When the electric-a1quantity supplied to apparatus 30 by secondary winding 24 and couplingdevice 20 indicates that the load connected to the transmission line isdrawing a predetermined high reactive power, circuit breaker 3 8 isoperated to connect capacitor across the line. Circuit breaker .38 isoperated to disconnect capacitor 35 from the transmission line when thereactive power traversing the transmission line reaches anotherpredetermined lower level.

The general construction of electrical coupling device 20 is illustratedin FIGS. 2 through 5. Referring to these figures, the coupling deviceincludes a hollow, essentially tubular post-type insulator 40 ofporeclain or the like which is open at the inner end and is usuallyclosed at the outer conductor-supporting end, although it may be open atboth ends. This insulator is formed with the usual radial ribs orflanges 41 customary in insulators supporting high voltage transmissionlines. The outer end of insulator 40 is designed to serve as a supportand anchorage for a high voltage current carrying transmission line,such as the line 21 of FIG. 1, or a bus bar in a generating station oran electrical substation. When insulator 40 serves to support a highvoltage transmission line, except one within a generating station or asubstation, the insulator is generally referred to as a line post. Onthe other hand, when the insulator 40 is used to support a bus bar orthe like within a generating station, a substation, or an adjacentswitching yard, it is generally referred to as a station post insulator.These two types of pos insulators differ from each other in manyrespects, as will be mentioned more fully hereinafter.

When the coupling device is used as a line post insulator, it usuallysupports a transmission line conductor which generally has asubstantially circular cross section. For this purpose, the closed outerend of insulator 40 may be formed with a semi-cylindrical cross sectiongroove extending diametrically thereacross, and the transmission lineconductor may be laid into this groove and secured in a suitable manner,as by being tied to the exterior surface of insulator 40 by wire or thelike. However, when the coupling device is used as a station postinsulator, the outer end thereof may support bus bars of various shapesas well as other equipment. For this purpose, special fittings are usedand, it is generally customary to provide the outer end of the insulatorwith a suitable mounting cap.

A feature of the present invention is that the coupling device, andparticularly the insulator 40, is arranged not only to support a lineconductor directly in engagement with a closed outer end, but also toreceive various mounting caps which may have different forms inaccordance with the particular conductor mounting arrangements to beused, such as the size and shape of bus bars, for example, and dependentupon Whether or not equipment in addition to a bus bar or the like is tobe mounted on the outer end of insulator 40. Therefore, as shown in FIG.2, the outer end of insulator 40 may be provided with a metal cap'42which may be anchored or supported thereon in any desired manner. Themetal of cap 42 is a non-magnetic metal, such as bronze, copper, brassor the like so that the cap does not effect the electric fieldsupporting the current carrying conductor supported thereby. In FIG. 2,and solely by way of example, the cap 42 is illustrated as having a flattop, but the outer surface of the cap may have any desiredconfiguration. Also, as shown in FIG. 2, the insulator 40 is illustratedas having a closed outer end, but in Certain cases the insulator mayhave an open outer end.

Insulator 40 serves as an enclosure and support for the inductivepick-up assembly which is generally indicated at 45. This inductivepick-up assembly, as will be described more fully hereinafter, includesat least one, and preferably plural, pick-up coils or windings, withwhich are associated one or more compensating or reference coils orwindings. In accordance with the invention, the several coils arecontained within an enclosure generally indicated at 50. This enclosureis made of a metal which has a very low electrical resistance or,correspondingly, a very high electrical conductivity. The metal may becopper, aluminum, or the like, and the high conductivity or lowresistance enables the metal enclosure to dissipate the elfects of theline current surges and disturbances, such as transients. Furthermore,it is important that the enclosures and its contents be protectedagainst corrosion. For this purpose, the highly electrically conductivemetal of the enclosure is further enclosed in a material which willresist corrosion. One expedient is to provide a stainless steel orplastic outer enclosure for the copper inner enclosure. Other corrosionresistance expedients may be used, however. For example, the innercopper, or the like, enclosure may be intimately associated with theouter stainless steel enclosure by physical bonding, metal deformation,or the like.

Furthermore, the can or shield surrounds the coil with an equipotentialfield, which may be at ground potential protecting the coil from thedeleterious effects of a high electric field.

The leads of the various coils or windings within the enclosure arebrought out to solid-type terminals 43 which are hermetically sealedwithin the enclosure 50, and conductors 44, of heavier gauge than thecoil leads, are connected to terminals 43 and brought out through theinner end of insulator 40. The coil or winding leads are generallyrelatively light gauge stranded wire, whereas the conductors 44 areheavier gauge stranded wire and thus capable of withstanding greaterstress.

The interior of the insulator is filled with a suitable insulatingmedium. In FIG. 2, this is illustrated as a filling 46 of a pottingcompound having the proper dielectric strength and inertness forelectrical shielding. Alternatively, the insulating medium may be highlydielectric and/or electronegative gas such as, for example, sulfurhexafluoride. Other suitable insulating materials, known to the art, maybe used. An example of this is Sylgard, which is a silicone rubberpotting compound.

In the instance where a relatively solid insulating compound is usedwith an insulator 40, the assembly 45 may be supported by the pottingcompound. However, if the potting compound is not sufiiciently stable tosupport the assembly 45, or if a gaseous insulating medium is used, theassembly 45 may be supported upon a tube 49 mounted within insulator 40and through which conductors 44 are brought to the base of theinsulator.

In accordance with the invention, the inner end of the insulator isdesigned for various mounting arrangements and access to the coil leadsor to conductor 44. As illustrated in FIG. 2, the inner end of insulator45 may be closed by a metal mounting cap 47 which may be of any suitablemetal and need not necessarily be nonmagnetic. Solely by way of example,FIG. 2 illustrates a cable 48, comprising the conductors 44, as broughtout through a side of cap 47 by means of a suitable outlet or nipple 51serving to seal the cap which, in turn is sealed to the open inner endof insulator 40. For mounting purposes, cap 47 may be formed withsuitable tapped holes, such as indicated at 52.

FIGS. 3, 4 and 5 illustrate the internal arrangement of the coilassembly 45. The coil assembly includes two sets of coils, the outer setcomprising pick-up coils 55 and the inner set comprising compensatingcoils 60, which can be used not only for reference compensation, butalso for automatic compensation with respect to differences in effectivedistance of the conductor supported on the coup'ing device, particularlyon the insulator 40. This effective distance is determined largely bythe shape and size of the conductor, and it is important thatcompensation be made for differences in the effective distance of aconductor from the main pick-up coils 55.

It has been found that it is very difficult to derive two or morefunctions from a single coil or winding. By using two or more pick-upcoils in the assembly, each function can be derived from a separatecoil. While there are two coils 55 illustrated, it will be noted thateach of these coils is subdivided into three sections, each sectionconstituting a separate winding. Thus, in effect, there are six pick-upcoils in the coil assembly 45. For example, each coil 55 may comprisethree coil sections A, B and C which are separated from each other bysuitable separators 54.

The structure of the pick-up coils 55 and the compensating coil is ofconsiderable importance in the efficiency of operation of the couplingdevice 20. The

several coils 55 and 60 are wound on the usual coil forms or spools 56which embrace magnetic cores 57. The cores 57, which have high magneticpermeability, may be either solid, laminated or powdered, that is,sintered. An im portant feature of the core construction is theprovision of the enlarged magnetic pole pieces 58 which are onlyslightly smaller than the ends of spools 56. These magnetic pole piecesgreatly increase the efficiency of pickup of the magnetic fieldsurrounding the current-carrying line conductor.

All four coils are enclosed within the metallic cup, can or shield 50which, as described more fully hereinafter, is provided with a suitableinner end closure fitted or sealed thereto. The several coil leads, suchas indicated at 61 and 62, are generally relatively light gauge strandedwire and are brought out and soldered to the inner ends of the solidmetal terminals 43. These terminals are hermetically sealed within theenclosure for coil assembly 45.

As stated previously, relatively heavy conductors or leads, which alsomay be stranded, arc soldered or brazed to the outer ends of terminals43 and are brought out through the inner end of insulator 40. A groundlead 63 is soldered, brazed, or welded either to can 50 or to its base,and is also brought to the inner end of the insulator where it may begrounded in a manner described more fully hereinafter. While cores 57have been illustrated as having a square cross section, it will beunderstood that the cross section may be other than square, such ascircular. Furthermore, the magnetic pole pieces may have a circularperiphery rather than a square periphery.

As compared to a line post insulator, a station post insulator has amuch squatter appearance, even though it may have the same height.Station post insulators generally are provided with metal components,supports, or caps on their outer ends which are arranged to supportvarious types of bus bars or the like as well as, in some cases, otherassociated apparatus. The bus bars may be tubular, rectangular, square,or any other shape. Consequently, the effective height of the 'bus baris determined by its size and its shape. Thus, the effective height ofthe conductor relative to the main pick-up coils 55 within insulator 40is also dependent upon the size and shape of the particular bus barsupported on the insulator 40. The length of a station post insulator ismuch more critical that that of a line post insulator, for the reasonthat the station post insulator usually is closely associated with othernearby equipment.

FIGS. 6l2 illustrate one embodiment of the electrical coupling device ofthe invention as incorporated in a line a post insulator. The porcelaininsulator 65 has a construction which is closely similar to that of theporcelain insulator 40 of the coupling device shown in FIG. 2. Insulator65 has a closed outer end and an open inner end. The outer surface ofthe closed end is formed with a generally semicircular cross sectiongroove 66 extending diametrically thereacross and serving to support aline conductor, such as the conductor 21. The groove 66 also serves toattain a predetermined orientation of insulator 65 with conductor 21.The outer cap 42 of FIG. 2 is omitted.

The outer surface of the lateral wall of insulator 65, adjacent itsinner end is also formed with a rough surface indicated at 67, forcooperation with various types of metal closures. The inner edge of thelateral wall of insulator 65 is also formed, at one point in itsperiphery, with the outwardly opening notch 68 whereby conductors may belead out of the interior of the insulator. A metal cap 70 closes theopen end of insulator 65, and cap 76 may be formed of suitable metal,whether magnetic or non-magnetic, although non-magnetic metal ispreferred. Cap 70 is generally cup-shaped and includes an inwardlyextending center protuberance 71 whereby there is defined an annularchannel or gutter into which the inner end of insulator 65 is received.A suitable sealing material, such as a potting compound or cement, ofwhich portland cement is one particular compound, may be used to sealcap 70 to the inner end of insulator 65, the sealing material beingindicated at 72 as filling the annular recess in which is seated theinner end of insulator 65. Protuberence 71 is formed with an outwardlyopening tapped bore 73 which may threadedly engage suitable means foranchoring cap 70, and thus insulator 65, to a cross arm of a pole or toany other suitable supporting surface.

An internally threaded nipple 74 extends radially outwardly from cap 71and its interior communicates with the interior of cap 76 through anaperture 76. In mounting cap 75 on insulator 65, nipple 74 is radiallyaligned with notch 68. A grounding screw 77 is threaded into a tappedbore in the bottom or innermost surface of nipple 74. Nipple 74 isarranged to have secured thereto the male member 75M of a suitablemulti-terniinal connector 75 having a female member 75F. These multipleterminal connectors are well known, and are sometimes referred to as ANconnectors. For example, male member 75M may be bolted to nipple 74.

A coil assembly 80, which externally has the appearance of a coilassembly 45 of FIG. 2, is mounted within insulator 65 adacent the closedouter end thereof. For example, coil assembly 80 may be supported on abracket 81 which is, in turn, secured to and supported on the outer endof a relatively rigid tube 82 serving to bring out the coil leads to theinner end of the insulator. Tube 82 is suitably supported within theinsulator, for example by being imbedded within the sealing material 72,and the coil leads brought through tube 82 are extended through notch 68and aperture 76 for connection to appropriate terminals of maleconnector element 75M. A suitable insulating compound, such as a siliconrubber or the like, may be packed around coil assembly 80, as indicatedat 83. The ground wire having one end soldered or brazed to the metalcover of the coil assembly 80, has its other end bared and clamped inposition by grounding screw 77.

FIGS. 8-12 illustrate the details of the coil assembly 80. In theparticular embodiment of the electrical coupling device illustrated inFIGS. 6 and 7, which is a line post insulator device, generally only onepick-up coil is needed although a compensating coil may be provided.This coil is indicated at 85 in FIGS. 8-12 and is construction isidentical with the construction of coils 55 and 60, including themagnetic core 57, the magnetic end plates 58 and the spool 56. Coil 85is enclosed within a can or cup 50 which is identical in constructionwith the cup 50. Thus, cup 50* is formed from a highly electricallyconductive metal such as copper or the like and has an outer layer ofanti-corrosion material such as stainless steel or the like. Thereby thecoil 85 is protected against corrosion by the stainless steel or thelike, and is protected against transients, surges and the like by thehighly electrically conductive copper of can 50'. A base 84 closes theopen end of the cup 55 and is recessed within the cup, this baseincluding a peripheral flange 86 which may be sealed to the cup 55.

Coil 85 is mounted in a generally U-shaped bracket 87 which is supportedupon base 84. To maintain proper orientation of the coil relative to thesupport bracket, the arms of bracket 87 may be formed with bent overtabs 88 which engage in notches in magnetic pole pieces 58. Also theends of spool 56 may have rectilinear ribs 92 formed on their outersurfaces for lying against rectilinear edge of a magnetic pole piece 58.

Base 84 has a pair of solid metal terminals extending in electricallyinsulated relation therethrough. The coil leads, such as 43, and whichare of relatively light gauge stranded wire, are soldered to the innerends of terminals 90. The relatively heavier gauge, and generallystranded, conductors 44 leading through the tube 82 are soldered to theouter ends of terminals 90. Base 84 is further provided with a mountingbolt 93 by meahs of which the coil assembly 80 may be secured on themounting bracket 81.

FIGS. 13-17 illustrate the coupling device of the invention asincorporated in a station post insulator. Insulator 95 is open at itsinner end and closed at its outer end. The inner end of insulator95 maybe roughened, as at 97, and formed with a radially extending notch 98 inthe same manner as the insulator is formed with the notch 68. The outerend of porcelain insulator 95 is closed and is formed with a roughsurface 94. However, the insulator may also have other top and bottomfixtures secured thereto.

As illustrated in FIGS. 13 and 14, the bottom cap 100' which closes theopen lower end insulator 95 is cemented to the open end of the insulatorby means of cement 102. Cap 100 may be formed with one or more tappedholes 103 for receiving anchoring screws, bolts or the like, and isfurther formed with an internally threaded nipple 104 on which there maybe mounted the male member 105M of a multi-terminal connector similar tothe connector of FIG. ,6, and arranged to have a female connectorthreadedly connected thereto. An aperture 106 establishes communicationbetween the interior of nipple 74 and the gutter 101 in which the loweredge of insulator is cemented. In cementing cap to the lower end ofinsulator 95, aperture 106 is aligned with notch 98. The inner end ofnipple 74 is formed with a relatively small diameter threaded bore 108for receiving a grounding screw 107. From FIG. 14 it will be noted thataperture 106 is eccentric with respect to nipple 104. Furthermore, theouter face of nipple 104 is formed with threaded or tapped bores forreceiving bolts or the like to anchor fitting M to nipple 104.

A conductor mounting cap 110 is positioned on the closed upper end ofinsulator 95. While insulator 95 is shown as having a closed outer end,the outer end may be open and cap 110 may be used to close the insulatoras by being sealed thereto by cement or the like. Cap 110 is providedwith one or more tapped bores 111 for receiving bolts or the like foranchoring a suitable electric conductor to cap 110. For example, in astation post insulator, the cap 110 will generally support a bus bar ofa rectangular or tubular shape, and of various dimensions. The cap 110may also support other apparatus associated with the bus bar or with theelectric coupling device. It is also possible to use a top cap which isdesigned for engagement with the roughened surface 94, thus providingready interchangeability with respect to the conductor mounting capsused on insulator 95.

The electrical device shown in FIGS. 13-17 includes a sensing coilassembly 115 and a reference coil assembly 120. These two assemblies areheld in properly oriented and coordinated relation by means of astrap-type bracket generally indicated at 112. Bracket 112 is generallyrectangular in elevation, including a transversely extending bightportion 113, side legs 11-4, and overlapped inturned ends 116. Theseends 116 are apertured to receive a stud 117 in'the base of coilassembly 115, and to be anchored to this coil assembly by means of a nut118 threaded on the stud 117. An elongated nut 121 is secured to asimilar stud on the base of coil assembly and has threaded thereinto arelatively elongated stud 122 extending through an aperture in the bight113 of bracket 114. Lock nuts 123, engaged with stud 122 and on eitherside of bight 113, hold coil assembly 120 in vertically adjustedrelation with respect to coil assembly 115, and also in angularlyadjusted relation with respect to coil assembly 115. Stud 122 may extendinto a mounting tube 124. A relatively large diameter conductor tube 125is fixed into cement 102 and extends substantially centrally ofinsulator 95, this tube enclosing the conductors from the coilassemblies 115 and 120 and serving to lead these conductors to the basewhere they are brought out through notch 98 and aperture 106 forconnection to the terminal pins of male connector element 105M.

Referring to FIGS. 15 and 16, each of the coil assemblies 115 and 120includes an enclosure similar to the enclosure of the coil assembly ofFIGS. 8-12. This enclosure thus includes a cap, can, or cup 50" and abase 84' in the same manner as described for the coil assembly 80.Furthermore, base 84' is provided with a mounting stud, such as 117, andwith terminals 90' extending in sealed insulated relation therethrough.In this instance, however, both of the terminals 90, one of which is astart or S terminal, and the other of which is a finish or F terminal,are located near the periphery of base 84. Each assembly 115 and 120includes two coils. In the same manner as described for the coilassembly 80, each of the sensing and reference coils is wound on a spool56' and includes a magnetic core 57. The winding on each spool 56' isdivided into two sections by a separator 54' and, for each assembly 115and 120, the four windings are designated A, B, C and D. Magnetic polepieces 58 are provided for the coils, with each magnetic pole pieceextending across the end of a pair of dual windings, in association withthe magnetic cores 57.

The two dual windings of each coil assembly 115 and 120 are supported bya pair of L-shaped brackets 126 which are riveted or the like to base 84and have apertures receiving the ends of magnetic cores 57'. To hold thedual windings in proper angular orientation with respect to the magneticend plates 58 and the terminals 90', one end member of each spool 56 isprovided with an eccentric pin 127 which is arranged to engage in anaperture 128 in the adjacent magnetic end plate 58.

The coil assemblies 115 and 120 are encased within a potting compoundwhich may be a silicon rubber such as, for example, Sylgard, asindicated at 131.

Before the coil assemblies 115 and 120 are placed within insulator 95, amutual adjustment thereof is effected. First, the sensing coil assembly115 is rotated to obtain a maximum output. Then the sensing coilassembly is held stationary while the reference coil assembly 120 isrotated for maximum output. The height of the reference coils is thenadjusted, by loosening lock nuts 123, relative to the sensing coilsuntil the reference coil output is a predetermined percentage of thesensing coil output. The reference coil assembly is then locked inposition by tightening lock nuts 123, and the assembly 120 may be tapedto the bracket 112 to maintain the adjusted angular position. After thetwo assemblies, interconnected by the mounting of bracket 112, areplaced within insulator 95, the proper orientation of the combinedassembly is adjusted while measuring the sensing coil output. Thepotting compound 131 is then applied within the insulator 95.

Referring to FIG. 17, the coils or windings of each assembly 115 or 120may be connected in various relations as may be particularly appropriatefor any given situation. For example, the four windings A, B, C and Dmay be connected in series aiding relation or in parallel aidingrelation.

One of the primary features of the invention is the enclosure of thecoil assemblies which, as stated, has to be a material which has a verylow resistance or a very high conductivity, and may be copper or thelike. Thereby line current surges and disturbances can be protectedagainst. It is, however, equally important that the enclosure itself, aswell as its contents, be protected against corrosion. The copperenclosure should be encased or enclosed in a material which Will resistcorrosion, and one material is stainless steel which can be provided onthe exterior of an enclosure of a low resistance metal, such as copperor the like. However, other corrosion resisting materials may be used.

The interior of the porcelain insulator can be filled, or at leastpartially filled, with the usual compounds for such purposes, and whichare generally known as potting compounds. One of these potting compoundsmay be used. Othe r materials which may be used for insulating purposeswithin the porcelain insulator are that known as the potting compoundSylgard and the gas sulfur hexa- 1 1 fluoride. The conductor tube, suchas the tube 82 or the tube 125 may be used to support the coil assemblyor coil assemblies. However, these assemblies may be supported solely bythe potting compound.

The enclosure for the coil assembly provides surge shielding by virtueof containing copper or aluminum or other lower resistivity material,and also provides a corona shield. Shielding against corrosion isprovided by acid resistant material, such as stainless steel, nickel, or

other materials inert to nitric acid. The magnetic pole pieces providefor the capturing of the maximum primary conductor flux, and the solidheaders such as 90, provide terminations for the leads and connectionswithout permitting escape or entrance of air, gas, or moisture into thecoil assemblies.

A feature of the invention is the use of an inert gas within thehermetically sealed coil assemblies. This inert gas may be any one ofseveral types. Preferably, the gas is an electro-negative gas such as SPSuch an inert gas may be introduced within the porcelain housing orinsulator, to replace the potting compound. The use of anelectro-negative gas is very advantageous, particularly from thestandpoint of use of the coupling device with very high voltages. It isof interest to note that the insulation is provided, in the case ofusing a potting compound, by the combination of the insulator and thepotting compound. When using an clectro-negative gas, the totalinsulation is provided by the insulator plus the gas undersuperatmos-phe'ric pressure. It is much more practical, for example, touse such a gas in instances where there may be a metal plate at the topof the insulator, rather than to use a potting compound, as the gasitself can form the electrical insulation "between the metal plate andthe components within he insulator. The metal plate just referred to isused in the case wherein the insulator may be a ceramic tube open atboth ends with a metal plate closing the outer end. However, it shouldbe noted that a metal plate is used very frequently on top of aninsulator which is a ceramic tube having a closed outer end, so thatporcelain is interposed between the metal plate and the interior of theinsulator.

The importance of the several features of the invention will be apparentwhen it is considered that, when coils or windings are placed adjacentto high voltage lines, they are subjected to all of the electricaleffects of the high voltage lines. Thus, unprotected coils may bedamaged from the effects of transients caused by the lighting andswitching surges, or from the effects of the high electric field.

While specific embodiments of the invention have been shown anddescribed in detail to ilustrate the application of the principles ofthe invention, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What is claimed is:

1. A coupling device 'for inductive coupling to a high voltage powerline current conductor, and serving as a fixed insulating support forthe conductor, comprising, in combination, a high voltage hollowinsulator having a closed outer end and an open inner end, the exteriorof the closed end having means for receiving a current conductor on saidinsulator and enabling said insulator to be located in predeterminedangular orientation with respect to the longitudinal extent of thesupported conductor; a coil mounted within said insulator adjacent theclosed end thereof, with the axis of the coil in predeterminedorientation with respect to the longitudinal direction of a conductorsupported on the exterior of said closed end, and with the coil spacedinwardly from such conductor; an enclosure of highly electricallyconductive and non-magnetic metal enclosing said coil within saidinsulator; a metal base covering the open end of said insulator; meanssealing said base on said insulator; plural solid electricallyconductive metal terminals mounted in sealed insulated relation in awall of said enclosure; coil leads extending from said coil andconnected to said terminals within said enclosure; and output leadsconnected to said terminals exteriorly of said enclosure and extendingthrough and insulated from said base.

2. A coupling device for inductive coupling to a high voltage power linecurrent conductor, and serving as a fixed insulating support for theconductor, compirsing, in combination, a high voltage hollow insulatorhaving an open inner and a closed outer end, the exterior of said closedend having means for receiving and supporting a current conductor onsaid insulator, and enabling said insulator to be located inpredetermined angular orientation with respect to the longitudinalextent of a conducor supported thereon; a base covering the open end ofsaid insulator; means sealing said base on said insulator; a sensingcoil mounted within said insulator adjacent the closed end thereof andwith the axis of the coil in predetermined angular orientation withrespect to the longitudinal extent of the conductor supported on theinsulator, said sensing coil being 'sp'aced inwardly from a conductorsupported on said insulator; a compensating coil mounted within saidinsulator adjacent said sensing coil and adjustable relative to saidsensing coil to compensate said sensing coil for variations in theeffective heights of conductors supported on said insulator; and outputleads extending from said sensing coil and said compensating coilthrough and insulated from said base.

3. A coupling device for inductive coupling to a high voltage power linecurrent conductor, as claimed in claim 2, including means sealinglyenclosing said sensing and compensating coils in highly electricallyconductive and non-magnetic metal.

4. A coupling device for inductive coupling to a high voltage power linecurrent conductor, as claimed in claim 2, including an enclosure ofhighly electrically conductive and non-magnetic metal forming a sealedenclosure for said coils.

5. A coupling device for inductive coupling to a high voltage power linecurrent conductor, as claimed in claim 2, including a pair of highlyelectrically conductive and non-magnetic material enclosures, eachforming a sealed enclosure for a respective one of said sensing coil andsaid compensating coil.

6. A coupling device for inductive coupling to a high voltage power linecurrent conductor, and serving as a fixed insulating support for theconductor, comprising, in combination, a high voltage hollow insulatorhaving an open inner and a closed outer end, the exterior of said closedend having means for receiving and supporting a current conductor onsaid insulator, and enabling said insulator to be located inpredetermined angular orientation with respect to the longitudinalextent of a conductor supported thereon; a base covering the open end ofsaid insulator; means sealing said base on said insulator; a coilmounted within said insulator adjacent the closed end thereof with theaxis of said coil in predetermined angular orientation with respect tothe longitudinal extent of a conductor supported on said insulator; andwith said coil spaced inwardly from said conductor; said coil includinga tubular coil form on which said coil is wound, a core of magneticmaterial extending longitudinally through and beyond the ends of saidform, and laterally extending magnetic pole pieces secured on theprojecting ends of said core to increase the magnetic pick-up; andoutput leads extending from said coil through an insulator from saidbase.

7. A coupling device for inductive coupling to a high voltage power linecurrent conductor, and serving as a fixed insulating support for theconductor, comprising, in combination, a high voltage hollow insulatorhaving an open inner and a closed outer end, the exterior of said closedend having means for receiving and supporting a current conductor onsaid insulator, and enabling said insulator to be located inpredetermined angular orientation with respect to the longitudinalextent of a conductor supported thereon; a base covering the open end ofsaid insulator; means sealing said base on said insulator; a pair ofsensing coils mounted in laterally adjacent relation within saidinsulator adjacent the closed end thereof, with the axes of the sensingcoils in predetermined angular orientation with respect to thelongitudinal extent of a conductor supported on said insulator, and withsaid sensing coils spaced inwardly from such conductor; a pair ofcompensating coils mounted in laterally adjacent relation within saidinsulator, each adjacent a sensing coil, said compensating coils beingmounted for adjustment with respect to the associated sensing coils tocompensate said sensing coils for variations in the heights ofconductors supported on said insulator; highly electrically conductiveand non-magnetic metal sealingly enclosing said sensing coils and saidcompensating coils and provided with solid electrically conductive metalterminals extending inwardly and outwardly thereof; coil leadsconnecting said coils to inner ends of respective terminals; and outputleads connected to the outer ends of respective terminals and extendingthrough and insulated from said base.

8. A coupling device for inductive coupling to a high voltage power linecurrent conductor, as claimed in claim 7, in which each of said sensingcoils is subdivided into axially adjacent and coaxial sections.

9. A coupling device for inductive coupling to a high voltage power linecurrent conductor, as claimed in claim 7, in which said coil enclosingmetal comprises first and second highly electrically conductive andnon-magnetic metal enclosures forming sealing enclosures for saidsensing coils and said compensating coils, respectively, each enclosureincluding a substantially cup-shaped cap and a base sealed to said cap;each base having plural solid electrically conductive metal terminalsextending in sealed insulated relation therethrough; coil leadsextending from the coils Within each enclosure to the inner ends ofrespective terminals of the enclosure and electrically connected to thelatter; said first-named base being formed with an outlet nippleextending laterally therefrom and said insulator being formed with anotch laterally aligned with said nipple; a support tube extending fromadjacent said notch through said insulator; output leads extending fromthe outer ends of said terminals in insulated relation through saidsupport tube and outwardly through said notch and said nipple; a bracketadjustably mounted on said support tube and supporting said firstenclosure; and means adjustably supporting said second enclosure on saidbracket for adjustment relative to said first enclosure.

References Cited UNITED STATES PATENTS 2,467,531 4/1949 Lamphene et al.336107 XR 2,677,077 4/1954 Knudson 336-107 XR 2,945,912 7/1960 Imhof17430 3,091,731 5/1963 Stein 323-102 3,187,282 6/1965 Pierce et al.336-84 XR 3,251,014 5/1966 Stein 336- DARRELL L. CLAY, lri/mlryExaminer. LEWIS H. MYERS, Examiner.

T. J. KOZMA, Assistant Examiner.

